Glass fiber reinforced resin panels are useful for construction, as liners for cars and trucks, for food plants, in dairies and in other industries where there is need for a strong panel which is unaffected by chemicals and resistant to abrasion.
It would be very desirable to produce such panels which not only have great strength and durability but are more pleasing in their appearance. It is possible to paint or paint a design on the surface of the panel, but such a design would add expense in the manufacture of the panel and would be likely to be marred or destroyed by abrasion in normal use of the panel.
The use of printing to provide a decorative panel is illustrated in U.S. Pat. Nos. 3,313,676 and 3,734,807 which involve a laminate having a rigid base member, a print sheet over the base member and a transparent polyvinylfluoride film which is electrically treated or coated with an adhesive to cause it to adhere to the print sheet.
In patent application Ser. No. 673,869, filed Apr. 5, 1976, I describe a method and machine for making glass fiber reinforced resin panels. In accordance with the processes therein disclosed a cellulose film is laid down. On this is placed a layer of thermosetting resin, and over this is placed a layer of glass fibers. The structure, including the film, the resin and the glass fibers, are passed between rolls so as to press the glass fibers into the resin, remove air voids and compact the structure to a desired thickness. After this the structure is heated to cure the resin and the cellulose film is removed.
I modified the process above described by embossing the cellulose film used in that process and by using the embossed film as the carrier film to make the resin panel. Although such modified process was operable it presented difficulties which caused trouble is manufacture and resulted in a substantial amount of damaged product. It appeared that when the resin was pressed against the embossed film some of the resin would occasionally come through the film. Examination of the embossed film prior to its use did not reveal any holes or spongy areas through which resin could pass, but the occasions when, for some reason, the resin did pass through the film, resulted in degrading of the product and gumming of the machine. No amount of care in the embossing of the film seemed to affect the leakage of resin through the film through openings which, for want of a better term, are called "pin holes".